A bearing assembly of this kind is known from U.S. Pat. No. 5,803,616, which discloses a double-row taper roller bearing in which a grease retainer is mounted to an outer ring of the bearing between the two rows of tapered rollers, at a small-diameter end of the rollers. In a tapered roller bearing, grease lubricant is urged from the small diameter end of the bearing to a large-diameter end under the action of centrifugal force. Therefore, grease that is initially provided between the two roller sets may migrate relatively quickly to an axially outer side of the bearing, where the grease contributes little to the lubrication of the bearing. As a result, relubrication is required on a regular basis. Furthermore, the migration of the grease from the small diameter end to the large diameter end creates churning losses and friction.
The retainer disclosed in U.S. Pat. No. 5,803,616 has a ring-shaped channel which is axially delimited by two side walls of the retainer. The side walls have apertures for communicating the inner space of the channel with the bearing space. The grease retainer therefore allows some migration of grease to the bearing space but prevents the grease from migrating too quickly, even under the influence of centrifugal forces and shock loads experienced during operation.
The retention of grease between the two sets of rollers in a double-row taper roller therefore has benefits, but it is also important that the retained grease is able to contribute to the lubrication of the bearing, either in terms of grease migration or the migration of oil that bleeds from the grease.
In U.S. Pat. No. 3,913,992, a lubrication apparatus is disclosed, comprising a collar for supporting a mass of grease, mounted on a rotating part of a double-row tapered roller bearing, between the two roller sets. The collar has a support surface that faces the bearing axis of rotation and side walls that form a container for the grease mass. The collar is made of a mesh screen or of sheet with perforations, so that oil is released from the collar under the action of centrifugal force, while the grease body remains in place. The oil provides lubrication to the bearing contacts.
There is still room for improvement, however, in terms of defining a bearing assembly provided with a grease cartridge that enables a more controlled delivery of grease and/or oil during bearing operation.